I understand your concerns, people do care about languages though they shouldn’t. However, if you are starting your career, it would be better for you to focus on what is going to help you in the mid term. Maybe Kotlin is not that relevant in the job market today… but, would it be next year? If that is the case, you would be more ready than people that is focused on what is happening right now (Java). Look for the tools that let you do more, better, in an easier way (the job market will probably follow that trend, at a slower pace)… In my honest opinion, of course